镓(Ⅲ)与变色酸荧光反应及其应用研究

在pH＝4.4的乙酸-乙酸钠缓冲体系中,镓(Ⅲ)与变色酸反应生成新的荧光物质,在λex/λem＝242/370 nm,测得荧光强度增量△F与镓(Ⅲ)的含量在0～10 μg/25mL范围内服从比耳定律.探讨了荧光增强的条件.该方法用于样品分析的线性方程为:△F＝26.80c(μg/25mL)+0.011,相关系数r＝0.9991.测定煤样和煤矸石中镓含量分别为6.29 mg/kg和10.97 mg/kg,加标回收率在96.8%～103.5%之间,相对标准偏差＜5.0%(n=4),与分光光度法相比,结果满意.     

胡椒基荧光酮光度法测定粉煤灰中微量镓

在表面活性剂OP存在下,镓与胡椒基荧光酮(PIF)在pH 6.0 HAc-NaAc缓冲溶液中形成蓝紫色配合物,其表观摩尔吸光系数为8.51×104L.mol-1.cm-1,最大吸收波长为568 nm,配合物的组成比为n(Ga(Ⅲ))∶n(PIF)=1∶4。镓质量浓度在0~0.5μg/mL范围内符合比耳定律,镓(Ⅲ)的标准加入回收率在96.5%~102.1%之间。结合乙酸丁酯萃取分离干扰元素,用于测定粉煤灰中微量镓。     

新的吲哚类同型二聚体荧光探针测定蛋白质的分析研究

采用新的水溶性吲哚类同型二聚体探针Ⅰ,建立了一种新的蛋白质荧光分析体系.在酸性条件下,蛋白质分子能与吲哚探针发生结合作用,体系荧光明显增强并向长波方向发生红移,荧光强度与蛋白质质量浓度呈良好的线性关系,在最优条件下,牛血清白蛋白BSA的线性响应范围0.80～25.00 μg/mL,检出限(3σ/K)为0. μg/mL;用于模拟样品的测定,1.00,2.00和5.00 μg/mL的样品测定回收率为99.0%～102.0%,相对标准偏差1.8%～2.8%;与国家标准方法比较,结果测定偏差为1.0%～4.1%.     

对氯苯基荧光酮分光光度法测定锌渣中痕量镓

在表面活性剂十六烷基三甲基溴化铵存在下,镓(Ⅲ)与对氯苯基荧光酮形成红色的三元络合物.显色体系稳定,最大吸收波长为571 nm,表观摩尔吸光率为1.17×10 5L·mol-1·cm-1.镓(Ⅲ)质量浓度在8 μg/25 mL以内遵循比耳定律.利用磷酸三丁酯-煤油萃取镓后,用氯化铵溶液反萃取,能有效地消除干扰元素的影响,提高方法的选择性和灵敏度.方法用于锌渣等样品中痕量镓的测定,得到回收率与相对标准偏差值依次为97.6%～102.5%和1.6%～2.6%之间.     

快速测定生物样品中蛋白含量的同步荧光法研究

最佳实验条件下,基于脱氧尿苷与人血清白蛋白(HSA)相互作用,导致血清白蛋白的同步荧光光谱发生特异性变化,且体系的同步荧光强度和溶液中白蛋白的浓度呈良好的线性关系,建立了以脱氧尿苷为探针,运用固定波长同步荧光光谱快速测定生物样品中蛋白质总含量的新方法.深入考察了△λ值、反应介质、试剂用量、离子强度、加入顺序、反应时间等因素对测定的影响.在最佳实验条件下,体系的同步荧光强度与血清白蛋白在2.76～524.4μg/mL范围内的线性相关系数为0.9991,方法的检出限可达0.11μg/mL.运用本方法对人血清、唾液和尿液等生物样品进行测定并进行加标回收实验,回收率在98.0%～102.5%之间.对11份空白溶液进行平行测定,相对标准差为1.2%.用经典的考马斯亮蓝G-250(CBB)法做了对照实验,两种方法测定结果基本一致.还考察了一些常见离子和有机物存在时对蛋白质测定的影响.本方法已用于血清、唾液和尿样等生物样品中蛋白质总量的快速测定.     

纳米金-曙红Y体系荧光增强法检测异烟肼

基于异烟肼对纳米金-曙红Y体系的荧光增强作用,通过测定加入异烟肼前后体系荧光信号变化与异烟肼含量的关系,建立测定异烟肼的荧光分析方法.并探讨了实验机理,在优化的实验条件下,方法的线性范围为0.02～2.0 μg/mL,检出限为9 ng/mL.对异烟肼片中异烟肼含量进行了测定,测定值与标识值没有显著差异,加标回收率在96...     

荧光素-曙红Y能量转移荧光猝灭法测定微量白蛋白研究

在λex/λem=405/547 nm,于缓冲溶液和表面活性剂存在的情况下,荧光素和曙红Y能够发生有效能量转移,而牛血清白蛋白(BSA)的加入使得曙红Y荧光猝灭,该体系可用于微量蛋白质的测定。系统探讨了荧光素-曙红Y能量转移体系发生荧光猝灭的条件,最佳条件为:2.0 mL pH=3.8的B-R缓冲溶液,0.4 mL 0.05%曲拉通X-100,1.5 mL 1.0×10-4mol/L的荧光素水溶液,2.0 mL 1.0×10-4mol/L的曙红Y水溶液,最佳实验时间为溶液配制完成静置15 min后60 min内,最佳加入顺序为pH=3.8缓冲溶液+荧光素+曙红Y+曲拉通+蛋白质标准溶液或样品。在优化的实验条件下,蛋白质含量在0～2.0μg/mL范围内与荧光猝灭强度呈良好的线性关系。检出限为6.6 ng/mL;测定样品的相对标准偏差(RSD)在±5%以内;样品加标回收率为90.4%～95.3%。该法可用于人血清、牛奶中蛋白质含量的测定。     

催化分光光度法测定地质样品中微量镓

在25mL反应体系中加入3.0mL硫酸(1.0mol/L)-盐酸(5.0mol/L)混合酸,3.0mL碘酸钾溶液(0.05mol/L),1.5mL胭脂红溶液(0.50g/L),微量镓对碘酸钾氧化胭脂红的褪色反应有良好的催化作用,为此建立了测定地质样品中微量镓的催化分光光度法。方法的线性范围在0~100μg/L,工作曲线的线性方程ΔA=2.369CGa+0.223 6(相关系数r=0.999 6),检出限(3S/N)为1.0×10~(-3)μg/mL。方法应用于地质标准样品中微量镓的测定(分别是岩石标准样品GBW07120和水系沉积物标准样品GBW07301a),测定值与认定值相符,测定值相对标准偏差(n=6)均小于5%,结果满意。     

胶束溶液中钙黄绿素-荧光桃红间荧光共振能量转移的研究及应用

研究了钙黄绿素-荧光桃红体系的荧光共振能量转移机理及其在蛋白质测定中的应用.实验表明:在聚乙烯醇存在下,于HAc-NaAc缓冲液(pH 5.30)中,钙黄绿素与荧光桃红之间能发生有效的能量转移.根据Frster理论,探讨了钙黄绿素与荧光桃红分子间能量转移机理.结果表明:蛋白质的加入使钙黄绿素-荧光桃红体系发生荧光猝灭...     

水杨醛异烟酰腙与镓荧光反应的研究

本文研究了荧光新试剂水杨醛异烟酰腙与镓的荧光反应,用紫外光谱法测定了试剂离解常数。在此荧光体系中,荧光配合物λ_(ex)=395nm、λ_(em)=480nm。在pH3.8、60％(V/V)乙醇介质中,测定的线性范围为0～1.0 μg/10mL,方法灵敏度为4×10~(-4)ppm。用荧光法测定了配合物的组成比及表观稳定常数。建立了镓的新荧光光度法,将其用于地质样品分析,精密度和准确度良好。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.